Write an installable DOS device driver for printers.

; TITLE : WRITE AN INSTALLABLE DOS DEVICE DRIVER FOR PRINTER

.model small
.code
org 00h

device_header:
link dd -1                    ;end of device driver
attr dw 08000h            ;char device driver printer
strat dw strgy              ;define strategy(data structure)
intr dw intpt ;interrupt routine entry point
logicalname db 'PRINTF  '     ;logical device name
   
  ;end of device header
  ;request header

req_header_off dw ?
req_header_seg dw ?

msg db 10,13, 'PRINTER DRIVER INSTALLED$'

strgy proc far                           ; procedure for strategy routine
mov cs:req_header_off,bx            ; get address from es:bx
mov cs:req_header_seg,es
retf                                           ;used to return from system function
endp

;*******************************************************

intpt proc  far          ; procedure for interrupt routine

pushf
push ax              ; push all the contents on to the stack
push bx
push cx
push dx
push ds
push es
push ss
push si
push di
push sp
push bp

mov bx,cs:req_header_off      ; restore the address of systems device drivers
mov es,cs:req_header_seg

mov al,es:[bx+2]             ; get command word in al
cmp al,00h                    ; if 00 then need to initialize the printer
jne next                      ; else already installed
call init                      ; call initialization procedure

next:   cmp al,08h          ; if equal printer ready to write
        jne next1
        call write           ; call write procedure

next1:  mov ax,0100h
           mov es:[bx+3],ax
        pop bp
        pop sp
        pop di               ; pop all the contents
        pop si               ; in proper order
        pop ss
        pop es
        pop ds
        pop dx
        pop cx
        pop bx
        pop ax
        popf
        retf             ;  return from system function

intpt endp

;*******************************************************

write proc near           ; procedure for printing the contents

mov cx,es:[bx+18]
mov si,es:[bx+14]
mov ds,es:[bx+16]

again:  mov ah,00h         ; function for writing character to printer
        mov al,ds:[si]       ; character to be printed
        mov dx,00h           ; printer number (LPT1=0, LPT2=1....)
        int 17h
        inc si                  ; points to next character
        loop again           ; loop untill value in cx register
        ret
write endp                   ; end of write procedure

;*******************************************************

init proc near            ; procedure for initialization of printer

lea dx,cs:msg            ; print message
mov ah,09h
int 21h

mov ah,01h            ; function for printer port initialization
mov dx,00h            ; printer name (LPT1=0)
int 17h

lea ax,init
mov es:[bx+14],ax

push cs
pop ax
mov es:[bx+16],ax
ret
init endp
end

; output

;Microsoft Windows XP [Version 5.1.2600]
;(C) Copyright 1985-2001 Microsoft Corp.

;C:\Documents and Settings\mmcoe>cd\

;C:\>cd tasm

;C:\tasm>tasm printer.asm
;Turbo Assembler  Version 2.0  Copyright (c) 1988, 1990 Borland International

;Assembling file:   printer.asm
;Error messages:    None
;Warning messages:  None
;Passes:            1
;Remaining memory:  476k


;C:\tasm>tlink printer.obj
;Turbo Link  Version 3.0 Copyright (c) 1987, 1990 Borland International
;Warning: No stack

;C:\tasm>exe2bin printer.exe printer.com

;C:\tasm>